In general, ethylene has been widely used as one of the basic reaction chemicals in the field of petrochemical industry and fine chemical industry. It is well known that synthesis of ethylene from methane by dehydrogenation is conducted at relatively high temperature of about 1500.degree. to 1550.degree. C. through thermal or electric cracking reaction process.
However, this method causes some problems such as loss of an enormous amount of thermal energy and necessity of using high temperature equipment, and particularly severe corrosion of the reactor owing to high temperature.
As prior art describing synthesis of hydrocarbons by oxidative coupling and dehydrogenation in order to prepare lower hydrocarbons such as ethylene having a double bond by direct conversion of 5118654, Canadian Patent No. 2016675 and Japanese Patent Nos. 04352730, 04368342.
Above-referenced processes have more or less settled some disadvantages since the reaction is conducted at relatively lower temperature of about 700.degree. to 800.degree. C. However, since the reaction is conducted with oxygen, helium, nitrogen and N.sub.2 O as oxidation or dilution gas, variety of reactants and a large amount of by-proudcts such as CO.sub.2 are ensuing. Moreover, there are much difficulties in separating or purifying the reactants, let alone the inability to conduct a continuous process and the causation of a severe environmental pollution problem.
In the meantime, natural gas contains impurities such as carbon dioxide, H.sub.2 S and moisture other than methane as the major ingredient. These impurities may affect catalytic activity, if they are not purified and the reaction cannot proceed properly.